From quite a few people on the scene, we have been told that the powder represented most of the concrete.  That the amount of intact macroscopic chunks of concrete on the scene were negligible.  That basically everything was reduced to powder.  And incidentally, we also know that other things besides concrete were reduced to powder.  We know that contents of computers, exotic metals from computer chips, these sorts of things were also identified in the dust in very small particles, generally on the order of less than 100 microns in diameter.  So we have a real issue of mechanism as far as what in the process of this collapse could cause so many things to be pulverized so finely. 

For the towers to collapse the way we saw them collapse basically implies that the columns simply collapsed into themselves.  They telescoped straight down.  Steel keeps a lot of its structural integrity even when heated until you begin to approach the melting point you don't really see a catastrophic loss of strength, and this is what we're talking about, we're talking about basically vertical box columns collapsing into themselves which implies a complete loss of mechanical strength.

And as far as the initial impacts, this recent NSIT study made an interesting point about World Trade Center 2.  The film analysis showed that it oscillated for about four minutes after it was struck by the airplane, and the oscillation rate was identical to what would be expected for the intact tower.  Trade Center towers and most modern buildings are heavily redundant in the sense that the load bearing can be shifted to other members if some of them fail, and we saw that happen  in this case, stresses do re-distribute, but absent further weakening of the structural members, that distribution is limited.  It happens, the structure restabilizes and unless there is significant further damage it doesn't progress to a total collapse. 

World Trade 1 began collapsing from the very top after an hour and 40 minutes.  It's very hard to imagine office contents progressively heating up, hotter and hotter, over that period of time.  And for a building to collapse from the very top, which is the least heavily loaded, is also very odd, to say the least.

Just a couple of other anomalies, as we know, there were reports of explosions.  There were reports of underground explosions in both of the towers at the time of the impact.  From a building engineer by the name of Philip Morelli, there are interviews with him on the Web.  From the Naudet Brothers film, "9/11", you see that the lobby of the North Tower was extensively damaged with what looks like high explosives blast damage, and this was immediately after the plane collision.  But we know that on the weekend before there were power downs and there appear to have been evacuation drills going on throughout the previous week which suggests that at least some people knew that something was happening.  The power downs may represent a time window in which demolition charges would have been planted, although I think it's possible that they were also planted over a much longer period of time given the relative accessibility of the buildings.

Okay, that's all I have to say.  Thank you.

Ed Begley, Jr.:  Thank you Jeff King, very, very much.

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